Conventionally, a wiring board for mounting a semiconductor integrated circuit component (hereinafter referred to as “IC chip”) includes a capacitor in order to reduce switching noise of the IC chip and to stabilize the associated operational power supply voltage. When providing the capacitor in the wiring board, the capacitor is preferably formed near the IC chip, because the longer the wiring between the IC chip and the capacitor, the greater the increase in the inductive component of the wiring, thereby resulting in a decrease in the effectiveness of the addition of the capacitor. In this regard, Japanese Patent Application Laid-Open (kokai) No. 2005-39243 discloses a wiring board having a structure wherein a ceramic sub-core incorporating a capacitor therein is accommodated in a core board which is located directly under the IC chip.